Annealing effects

Its value at 25°C is 0.71 J/(g-°C) (0.17 cal/(g-°C)) (95,147). Discontinuities in the temperature dependence of the heat capacity have been attributed to stmctural changes, eg, crystaUi2ation and annealing effects, in the glass. The heat capacity varies weakly with OH content. Increasing the OH level from 0.0003 to 0.12 wt % reduces the heat capacity by approximately 0.5% at 300 K and by 1.6% at 700 K (148). The low temperature (<10 K) heat capacities of vitreous siUca tend to be higher than the values predicted by the Debye model (149). 

The present review shows how the microhardness technique can be used to elucidate the dependence of a variety of local deformational processes upon polymer texture and morphology. Microhardness is a rather elusive quantity, that is really a combination of other mechanical properties. It is most suitably defined in terms of the pyramid indentation test. Hardness is primarily taken as a measure of the irreversible deformation mechanisms which characterize a polymeric material, though it also involves elastic and time dependent effects which depend on microstructural details. In isotropic lamellar polymers a hardness depression from ideal values, due to the finite crystal thickness, occurs. The interlamellar non-crystalline layer introduces an additional weak component which contributes further to a lowering of the hardness value. Annealing effects and chemical etching are shown to produce, on the contrary, a significant hardening of the material. The prevalent mechanisms for plastic deformation are proposed. Anisotropy behaviour for several oriented materials is critically discussed. 

Fig. 2. Curves showing annealing effects (140 Q on diphenylarsonic acid ( jAsOtOH)). Note the rise in the yield of radioactive arsenic (Redrawn from Grossmann )...

Fig. 6. Isochronal (15 min) annealing effects for various products from neutron-irradiated dicyclopentadienyldiiron tetracarbonyl (Cp2Fe2(CO)4) (From Kanellakopulos-Drosso-pulos and Wiles S )...

Maddock and Sutin (56) observed the formation of numerous oxygenated products in neutron-irradiated AsPhj which, they argued, must have come from reaction of AsPh radicals with oxygen or water during the separation. The annealing effect of heating at 45° led to increased yields of AsPhj, while AsPhj products first increased and then decreased. This was interpreted as showing the involvement of phenyl radicals in a series of consecutive reactions ... 

Fig. 3. Stepwise thermal annealing effect in MofCO). From Groening and Harbottle (23).

It is likely that the answers to these questions will come only from more selective and sophisticated experiments than have been done hitherto, although some useful directions have been established. The use of high-sensitivity electron spin resonance for the study in situ of anticipated radical species will likely be possible, if the background signals from other radiation-produced species are not too intense. Studies of the chemistry of implanted atoms and ions in solid organometallic substrates will make it possible to start with totally unbound atoms which suffer no Auger ionization and thus to simulate the extreme of the total recoil. Careful studies of the thermal annealing effects, especially in the presence of reactive atmospheres, will... 

This sometimes does not appear very satisfactory [61-63] several alternative explanations of the annealing effect have been considered ... 

Ranjith, R. John T. T. Kartha C. S. Vijayakumar K. P. Abe T. Kashiwaba Y. 2007. Post-deposition annealing effect on In2S3 thin films deposited using SILAR technique. Mater. Sci. Semicond. Process. 10 49-55. 

F.R. Zhu, C.H.A. Huan, K.R. Zhang, and A.T.S. Wee, Investigation of annealing effects on indium tin oxide thin films by electron energy loss spectroscopy, Thin Solid Films, 359 244—250,... 

Ramsey theory, 22 201-204 Random-fragmentation model, Szilard-Chalmers reaction and, 1 270 Random-walk process, correlated pair recombination, post-recoil annealing effects and, 1 288-290 Rare-earth carbides, neutron diffraction studies on, 8 234-236 Rare-earth ions energy transfer, 35 383 hydration shell, 34 212-213 Rare gases... 

Different field-annealing effects on the magnetostriction are evident across the whole composition range, as summarised in fig. 19. For the Co-rich alloys, b increases... 

Fig. 21. X-ray diffraction pattern of the annealing effect on polypropylene quenched to the CD-glass (control trace). The changes may suggest a glass transition at 340 to 360 K. Curve courtesy of Dr. W. W. Cox of the Research Laboratory of Hercules Inc.

---